Improvements relating to devices used for convergent beams therapy with moving beam technique

摘要

686,828. X-ray apparatus. SIEMENS REINIGER-WERKE AKT.-GES. April 27, 1949 [Nov. 26, 1948], No. 11249/49. Class 98 (i). [Also in Group VI] In a device for irradiating a part of a body continuously while keeping the irradiation of other parts to a minimum, the source of radiation is moved along a spiral path around the mean axis of the space swept out by the beam while so directing the beam that it always passes through a fixed point located (in the use of the device) at the seat of the disorder to be treated. Radiation may consist of X-rays, electrons, neutrons, ultrasonic sound waves, electromagnetic radiation and the like. The source of rays may be moved, during the irradiation, over a part of the surface of a sphere. In one form of the device, the inner surface of a hemispherical housing has a spiral track. A unit consisting of a source of rays and driving motor moves on the track by means of a spur-wheel driven by the motor. In the form shown, the apparatus has a channelsectioned ring 3 with rollers 4 whereby it may rotate in a fixed channel-sectioned ring 5. A pair of parallel arcuate channel-sectioned rails 1 act as guides for a carriage 7 having rollers 8 engaging rails 1 and carrying an X-ray tube in a casing 9. The tube is rotatable about the axis 31 of the cone of rays, which passes through the centre 11 of the arcuate rails 1. The carriage 7 moves over a part of rails 1; on the opposite side of the rails a gear-box 13 is mounted together with an electric motor (not shown) with a driving shaft 13 driving a shaft 18 through a worm drive. One end of shaft 18 has a pinion 19 engaging a toothed rack 20 on ring 5 whereby ring 3 is rotated by the motor. The other end of shaft 18 is geared to a shaft 24 carrying a cam at each end. The carriage is connected to the cams by a cord 27, and by a cord 28 passing over a pulley 29 on ring 3 opposite the gear-box. When the motor is started, ring 3 rotates and cords 27, 28 are wound and unwound at equal rates to move carriage 7, the movement becoming faster as the carriage approaches the central position. The motor may then be reversed. Preferably, switches (not shown) operated by the carriage switch the X-ray tube on just after the motor starts and off just before the carriage reaches the central position, and at that position switch off or reverse the motor. Supply to the motor is by moving contacts travelling on rails connected to ring 5. To prevent twisting of the supply cable to the X-ray tube, the tube may be rotated about its axis through 180 degrees during half a revolution of ring 3, and rotated oppositely during the other half of the revolution. For this purpose the X-ray tube carriage has rollers engaging the inner surface of a housing (not shown), which surface is partly cylindrical but has a space in which the tube can turn.